Fade resistance depends mainly on your chosen color...LITERALLY!

Earth/mineral-based colorants fade the least (Blacks, Red-Oxides, Yellow-Oxides, Browns & Umbers).

Artificially created colorants (Reds, Magentas, brigther Yellows, etc.) fade the most in bright sun.
* A Red door/trim that's in the shade a lot, obviously, won't fade that much.
* A Red door in full sun will look "pink" relatively fast...

High-ends paints, like C2 Exterior, FPE, a couple high-end BM & SW lines have better colorants.
* C2 for instance, uses 2 RED colorants...HR=High-strength Red; and RL=Red low.
* Also two Yellows, two Blues, & two Blacks.
* Only a ~couple companies have TWO high-strength colorant versions. These type of colorants are pretty color-stable outside. They should be...you could feed a family of 3 at a restaraunt for what a Qt. of C2 High-strength Red costs!
* FPE uses colorant PASTES for most of their series. VERY high-Q stuff there!

Faron

Also, oil based paints fade much quicker than latex or acrylic paints.

If you pick a slightly greyed medium to light shade, it's less likely to look faded because it's not intense.